And I'm Robert Siegel. The State Department has confirmed that a U.S. citizen was involved in the suicide bombing in Syria earlier this week. Today, State Department spokeswoman Jen Psaki confirmed the man's identity in response to a reporter's question.

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UNIDENTIFIED REPORTER: Can you confirm, at least, the name that he went by - as was published - Abu Huraya al-Amriki?

JEN PSAKI: That is correct. Or the translation is, the American.

SIEGEL: Psaki said he is believed to be the first American involved in a suicide bombing in Syria since the start of the war there. For more on this story, I'm joined now by NPR's Pentagon correspondent Tom Bowman. And, Tom, this man was first identified as an American by jihadist websites. What do we know about the attack that he is believed to have carried out?

TOM BOWMAN, BYLINE: Well, Robert, NPR contacted a spokesman for the Al-Nusra Front, one of the al-Qaida affiliates fighting against the Syrian government. And this spokesman said the American had been killed, as he put it, in combat. And in a statement, the group said he died Sunday, along with several other fighters after conducting one of four suicide bombings. They said the American detonated a truck loaded with 16 tons of explosives, near a restaurant in northern Syria, that had been converted into a Syrian military base.

SIEGEL: What else do we know about his background?

BOWMAN: Well, we still don't know his given name. But U.S. officials confirm he has ties to Florida, and he has been known to law enforcement in this country for some time. His family right now is being questioned and there's no other word from law enforcement officials about...

SIEGEL: Yeah.

BOWMAN: ...About his background.

SIEGEL: Now, the jihadist websites posted photos of this American before the attack. Tell us about those.

BOWMAN: Well, that's right. One website posted a picture. They said it showed the American. He's young, smiling, wearing Arab garb and cuddling a cat. And this connection to the jihadist groups highlights what American officials and allies have been worried about for some time. Fighters from the U.S. and Europe heading to Syria and joining al-Qaida and its affiliates, getting training, becoming more radicalized. And then maybe returning to mount attacks on their own countries.

SIEGEL: Is there any sense of how many Americans, and Europeans for that matter, are fighting alongside al-Qaida and its affiliates in Syria?

BOWMAN: Well, first of all, officials estimate the total number of al-Qaida fighters and their allies are roughly about 26,000 in Syria. And that's a number growing steadily over the past two years. Of that number, they estimate as many as 100 Americans are fighting on the ground. No sense about how many Europeans yet. But again, France and Turkey are especially concerned about this. And this gets into the issue we heard this week, when President Obama gave the commencement speech at West Point. He said he wants to ramp up support for the moderate rebels fighting Assad, and one reason for this is the growing strength of the jihadi groups and to try to blunt their growing power. These moderate groups are locked in battles, not only with Assad's forces, but also with these jihadi groups who are very aggressive fighters, well led, and well trained.

SIEGEL: That would include of course the Al-Nusra Front, as you say...

BOWMAN: Absolutely.

SIEGEL: ...The group that claimed an affiliation with this, so far unidentified American. Do we know? Does the U.S. say whether most of the Americans who've gone over there have in fact been fighting for al-Qaida affiliated groups, as opposed to the more moderate forces? Or...

BOWMAN: Oh, yeah. They believe that these Americans in particular are fighting for the jihadi groups right now. But again, the concern is - would they come home and mount attacks in this country? And again, the Europeans are also quite concerned about that as well.

SIEGEL: OK, Tom. Thank you very much.

BOWMAN: You're welcome, Robert.

SIEGEL: That's NPR Pentagon correspondent Tom Bowman talking about the confirmation today from the State Department that indeed an American was involved in a suicide bombing in Syria earlier this week. Transcript provided by NPR, Copyright NPR.